Power chuck



V. V. K. SUNDT Aug. 21, 1951 POWER CHUCK 6 Sheets-Sheet 1 Filed Dec. 19, 1946 Hal.

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POWER CHUCK Filed Dec. 19, 1946 6 Sheets-Sheet 2 5 l4 0 v 9 J llllll "I, 7 A k Q nn" 7 8 l jz gzndi v 9 U011 2'0: 5 BY \\T fzwfii,

'V ATTORNEY:

Aug. 21, 1951 Filed Dec. 19, 1946 v. v. K. SUNDT POWER CHUCK 6 Sheets-Sheet 5 INVENTOR. V290 uonKrogh Sandi AT TORNEY Aug. 21, 1951 v. v. K. SUNDT 2,565,330

POWER CHUCK Filed Dec. 19, 1946 6 Sheets-Sheet 4 INVENTOR. W90 'uonii'rogiz Szznclf ATTORNEY v. v. K. SUNDT 2,565,330

Aug. 21, 1951 I POWER CHUCK 4 Filed Dec. 19, 1946 6 Sheets-Sheet 5 4/ 1 42 FIG.5.

INVENTOR.

l/zgo von Krqgh Saudi VZQ-Zw ATTORNEY.

v. v. K. SUNDT 2,565,330

POWER CHUCK Aug. 21, 1 951 6 Sheets-Sheet 6 Filed Dec. 19, 1946 INVENTOR.

% van K'z'qgh Sundz BY ATTORNEY.

Patented Aug. 21, 1951 POWER CHUCK Vigo Von Krogh Sundt, Madison, Wis., assignor to Gisholt Machine Company, Madison, Wis., a corporation of Wisconsin Application December 19, 1946, Serial No. 717,212

4 Claims.

This invention relates to a power chuck and has been embodied in a high speed lathe chuck which may be designed for either hydraulic or air actuation.

One of the principal objects of the invention is to provide a fluid pressure operated collet chuck in which the fluid pressure is applied to move the collet and is substantially relieved of back pressure in operation at predetermined chucking stations.

Another object is to provide a power chuck which will accommodate work of a larger range in size without requiring readjustment.

Another object of the invention is to more readily relieve the operating yoke connections with the rotary chuck from pressure and wear after chucking and during rotation of the spindle and chuck.

Another object is to provide a balanced con struction for the rotary parts of the chuck adapt-- ing the same for use with high speed lathes and the like.

Another object is to provide a substantially greater leverage and chucking power without increasing the size or number of parts.

Another object is to reduce the mass of the rotary part of the chuck.

Another object is to simplify the chuck struc-- ture and actuating parts therefor.

Another object is to provide for use of the full size of the spindle bore by providing an external chuck and eliminating the pull sleeve.

An embodiment of the invention is illustrated in the accompanying drawings in which:

Figure 1 is a vertical axial section through the chuck and the end of the headstock housing and spindle on which it is mounted, and showing the chuck in open position;

Fig. 2 is a horizontal axial section taken on line 2-2 of Fig. 1;

Fig. 3 is a vertical transverse section taken on line 3-3 of Fig. 1 through the centers of the lever arm rollers, and showing the operating yoke;

Fig. 4 is a front elevation of the chuck with parts broken away and sectioned to show the keying of the collets to the body of the chuck;

Fig. 5 is a horizontal axial section taken through the power cylinder and control valve on line 55 of Fig. 1;

Fig. 6 is a detail plan View of the slide of the chuck showing the cam and lever construction;

Fig. 7 is a detail section through the base of a lever and the body taken on line 1-11 of Fig. 1;

Fig. 8 is a section corresponding to Fig. 1 and showing the parts operated to chucking position upon a workpiece;

Fig. 9 is a detail view corresponding to Fig. 6 showing the lever in the position of Fig. 8; and

Fig. 10 is a detail section showing the key between the jaws and slide.

The chuck comprises, in general, a stationary chuck housing I secured to the headstock 2 of a lathe or the like, and a rotary chuck body 3 secured to the operating end of the spindle 4 of the lathe for rotation within the housing I.

A collet sleeve 5 is disposed for relative longitudinal movement within body 3 and has its forward end split into a plurality of circumferentially spaced collet fingers t constituting jaws which are adapted to move radially to grip and release the work under the influence of complementary conical surfaces of the fingers 6 and the body 3 determined by longitudinal movement of collet sleeve 5 within body 3.

The collet fingers 5 are loosely spaced and prevented from distorting due to torque, by means of keys '5 disposed therebetween in recesses in their edges and in corresponding slots in the conical surface of the chuck body 3. Screws 8 secure the keys 1 to the chuck body 3 and prevent displacement of the same.

The collet sleeve 5 is operated by a pusher sleeve 9 to which it is threaded at the rear end of the chuck, and which in turn is operated by a plurality of levers Hi from a slide H.

A fluid pressure cylinder l2 in housing I operates slide II by means of a yoke lever :3 or by other suitable means.

The collet sleeve 5 is recessed centrally to receive a split ring I l disposed between the forward end of pusher sleeve 9 and an abutment in the collet fingers 6. The ring M has recesses 15 therein to accommodate the inner ends of the corresponding levers l0 and serves to close the slots between fingers 6 and prevent dirt from passing therethrough to the spaces provided for the levers.

The ring l4 should have a substantial clearance at one end to provide for adjustment of the collet sleeve 5 relative to pusher sleeve 9 by means of the threaded connection therebetween.

The pusher sleeve 9 is prevented from turning relativ to body 3 and to collet sleeve 5 to which it is threaded, by means of a stud l6 threaded through body 3 into a keyway H in sleeve 9.

The levers l0 extend longitudinally of the chuck in corresponding circumferentially spaced recesses l8 in the outer surface of the chuck body 3.

The inner end of each lever Ill is pivoted in the chuck body 3 by a radially extending circular projection I 9 which fits in a bushing 20 in body 3.

The inner end of projection IQ of lever H) extends into a recess l5 and is substantially semicircular in cross section with its back side disposed at an angle to advance one edge 2| thereof rearwardly in operative contact with the front edge of pusher sleeve 5 at all times.

The outer end of each lever H] has a pin 22 extending radially outward therefrom into an opening 23 extending longitudinally of the cylindrical slide H which encircles body 3. A roller 24 is mounted on pin 22 and is held thereon by the clip spring 25 encircling pin 22 in a groove 26 therein for the purpose.

The slide I l is generally cylindrical and rotates with body 3. The slide II is disposed to move longitudinally upon body 3 to operat levers [0.

The opening 23 in slide II for each lever I is of sufficient length longitudinally of the slide to accommodate the roller 24 for the maximum distance of slide movement, and is of a width preferably substantially exceeding the diameter of the roller.

One side of each opening 23 constitutes an operative cam 2'! for actuating the corresponding lever H3 by moving roller 24 in a direction generally circumferential of body 3 as it follows the cam in response to longitudinal movements of slide l l.

The cam surface 21 for each opening 23 has a step shape and is disposed generally at an angle to the longitudinal center line of the opening wherein it is closer to the center line at its forward end than at the rear end.

The cam surfac 27 faces in a direction to bias lever III in a direction tending to hold the rounded edge 2| in contact with pusher sleeve 9.

When slide H is moved rearwardly on chuck body 3, the levers [0 are operated by cam surfaces 21 pressing against rollers 24 to cause the corresponding edges 2| to push sleeve 9 rearwardly, thereby pulling collet 6 against the conical inner surface of body 3 and contracting the collets to grip a workpiece 28.

Movement of slide l l forwardly of chuck body 3 results in a release of the chucking pressures and the workpiece 28 then can be readily removed by a forward pull thereon which releases the collet fingers 6 in body 3.

For the purpose of effecting rotation of slide l with body 3, a plurality of roller supports are provided to counteract the pressure of rollers 24 against cam surfaces 21. Each roller support comprises a roller 29 mounted on a pin 30 projecting radially from body 3 in a circumferential line with rollers 24, and each roller 29 rides in a corresponding longitudinal groove 3! in the inner surface of slide II where it presses against a wall of the groove in a direction opposite to the direction of pressure of rollers 24 against cam surfaces 21.

In the construction shown there are only two levers l0, disposed diametrically opposite in body 3, and there are two corresponding rollers 29, each disposed near a corresponding lever ID with the groove 3i adjacent the cam side of the corresponding opening 23. Where more than two levers ll! are employed a corresponding number of rollers 23 should be used. However, by employing only two levers ID with their corresponding edges 2| disposed diametrically opposite there is less tendency to bind collet sleeve and closer fits may be employed between the collet sleeve 5, the body 3 and the side I I.

The steps 32 of cam surfaces 2'5 are scalloplike and constitute alternate short increments in length of cam step approaches 33 disposed at an angle to the longitudinal center line of the corresponding opening 23, and intermediate step increment of length extending parallel to the longitudinal center line of the opening 23 and to the axis of the chuck.

When a roller 24 rides along the inclined step approaches upon rearward movement of slide H, the corresponding lever l0 pushes sleeve 9 rearwardly to tighten the collets 6 upon the workpiece 26. Upon reaching the desired chucking pressures, the roller 24 rests upon a step 32 which is non-inclined and which merely serves to hold lever [0 in position to maintain the chuck tightly closed upon the Work. The slide ll will not tend to move in either direction by reason of the chucking forces.

The number of wedge steps 32 employed may depend upon the size of roller 24 and the length of cam surface 21 required by the movement of slide ll. In the construction illustrated four steps 32 in addition to the release position for roller 24 were found to be adequate and to provide a desirable range to accommodate ordinary work tolerances.

The operation of slide II by yoke lever l3 and cylinder I2 is accomplished by a flange 34 on slide H and which is embraced by shoes 35 at the lower ends of the opposite arms 35 of the yoke lever.

The lever 13 is pivoted at 3! in the housing I, and its upper end is bifurcated to embrace a reciprocating rod 38 which constitutes a piston rod for piston 39 in cylinder [2. The bifurcated upper end of lever I3 has its members disposed in recesses 46 on each side of rod 38 and curved to maintain contact with the walls of the corresponding recesses in a horizontal line in the plane of the center line of rod 38.

Reciprocation of rod 38 forwardly by fluid pressure in the rear end of cylinder [2 acting against the full face of the rear side of piston 39 pushes lever 43 forwardly pivoting the same to move shoes 35 and slide ll rearwardly to operate the chuck and grip workpiece 28.

Reciprocation of rod 38 rearwardly by fluid pressure in the forward end of cylinder [2 acting against the front side of piston 39 pulls lever l3 rearwardly pivoting the same to move shoes 35 and slide ll forwardly to release the levers ID and permit release of the work 28 by collet fingers 6.

The operation of piston 39 is controlled by a manually operable slide valve 4| which controls the entrance of pressure fluid to cylinder l2 and the exhaust of fluid therefrom.

Valve 4| is disposed in housing I alongside of cylinder l2 at the top of the housing, the cylinder being generally parallel to the axis of the chuck.

The valve 4! may be constructed in any suitable manner to provide the desired control for piston 39 by admitting pressure fluid selectively to the opposite ends of cylinder l2 and simultaneously exhausting fluid from the other end, and by providing a neutral position in which the fluid in the opposite ends of the cylinder is equalized in pressure as by connecting both ends simultaneously to drain.

The slide 42 in valve 4| is operated by a pin 43 carried by the short arm of pivoted lever 44 on top of housing I.

The manual operating lever 44 should be biased to a normal neutral position by spring detents 45 or the like so that it does not retain the operating stress upon the parts after the chuck is operated to gripping or release position.

The chuck of the present invention is adapted for high chucking pressures and for high speed lathes where a balanced rotary structure is desired. All rotary parts are balanced in the chuck and there is no distortion created by any lack of balance.

By employing the wedge step cams for operating the levers ii], a very effective means is provided for avoiding back pressure upon the shoes 35 and lever l3. The wedge step cams also serve to provide for chucking of work which may vary in diameter due to tolerances in manufacture.

Where work of different diameter is to be chucked, the chuck may be adjusted by removing keys 1 and turning collet sleeve 5 a quarter turn or more in the desired direction, either in or out, and then replacing keys 1.

The collet sleeve 5 may be of substantially the same inside diameter as the spindle bore of the lathe so that the chuck will take stock of a diameter substantially as great as that which will pass through the spindle.

The chuck illustrated provides for contraction of the collet fingers 6 upon rearward pull of the collet sleeve 5. If desired, it is possible to reverse the action by reversing the inclined surfaces of the fingers and body, to thereby provide for contraction of collet fingers 9 upon a forward push of sleeve 5, as where it is desired to abut the 'work against a center or the like.

The invention may have various embodiments within the scope of the accompanying claims.

I claim:

1. A power chuck for high speed lathes and the like, comprising a rotary cylindrical chuck body, a collet sleeve mounted for relative longitudinal movement therein and for rotation therewith, said collet sleeve being split at one end to provide a series of circumferentially spaced collet fingers operable radially by complemental inclined surfaces between the fingers and the chuck body in response to longitudinal movement of the collet sleeve, a plurality of operating levers fulcrumed in said body with outwardly extending crank pins for operating the same and having their inward short arms engaging corresponding abutments on the collet sleeve to move the latter longitudinally of the body, a slide member encircling said body and rotatable therewith, said slide member having a plurality of longitudinally extending recesses therein for receiving the operating crank pins of the corresponding levers, one side of each recess constituting a cam disposed to engage the crank pin and operate the outer long arm of the corresponding lever in response to longitudinal movement of the slide in at least one direction, each cam having steps therein providing a series of alternate inclined and non-inclined increments relative to the corresponding lever to prevent back pressure from the chuck on the operating mechanism, and means to operate said slide member to effect operation of the chuck.

2. A power chuck for high speed lathes and the like, comprising a rotary cylindrical chuck body, a collet sleeve mounted for relative longitudinal movement therein and for rotation therewith, said collet sleeve being split at one end to provide a series of circumferentially spaced collet fingers operable radially 'by complemental inclined surfaces between the fingers and the chuck body in response to longitudinal movement of the collet sleeve, a plurality of operating levers fulcrumed in said body with outwardly extending crank pins for operating the same and having their inward short arms engaging corresponding abutments on the collet sleeve to move the latter longitudinally of the body, a slide member encircling said body and rotatable therewith, said slide member having a plurality of longitudinally extending recesses therein for receiving the operating crank pins of the corresponding levers, one side of each recess constituting a cam disposed to engage the crank pin and operate the outer long arms of the corresponding levers in response to longitudinal movement of the slide in at least one direction, each cam having steps therein providing a series of alternate inclined and non-inclined increments relative to the corresponding lever to prevent back pressure from the chuck on the operating mechanism, and power mechanism for operating said slide selectively in opposite directions, said mechanism having a normal neutral position at all times except when moving said slide.

3. A power chuck for high speed lathes and the like, comprising a rotary cylindrical chuck body with a plurality of collet fingers therein, a collet operating ring, a plurality of levers fulcrumed in said chuck body to pivot about axes lying substantially radially of said chuck to operate said ring, a slide encircling said body and disposed to rotate therewith, said slide having longitudinally inclined cam surfaces having a series of spaced increments disposed parallel to the axis of the chuck and separated by step cam surfaces, means to move said slide longitudinally of the chuck body whereby the cam surfaces of said slide effect pivotal movement of corresponding levers in a direction substantially circumferential of the chuck to operate said ring and collet, the spaced increment and step cam surface of said ring serving to retain the ring in a selected longitudinal chucking position, and the radial disposition of the lever axes causing any back pressure from said collet and levers to be exerted upon said slide only in a circumferential direction corresponding to its direction of rotation.

4. A power chuck for high speed lathes and the like, comprising a rotary cylindrical chuck body with a plurality of collet fingers, a collet operating ring, a plurality of levers fulcrumed in said body to operate said ring and having rollers mounted on their arms opposite the ring, a slide encircling said body and disposed to rotate therewith, said slide having a longitudinally inclined series of cam surfaces, each of the cam surfaces being of arcuate shape substantially complement the curvature of said rollers and being separated by step cam surfaces, means to move said slide 1ongitudinally of the chuck body whereby the cam surfaces of said slide effect pivotal movement of said levers, the arcuate and stepped surfaces of said ring serving to retain the rollers and ring in a selected longitudinal chucking position.

VIGO VON KROGH SUNDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 442,230 Libby Dec, 9, 1890 487,245 Briggs Dec. 6, 1892 594,077 Gauthier Nov. 23, 1897 685,063 Allen Nov. 5, 1901 952,149 Smith et al Mar. 15, 1910 1,818,305 Class Aug. 11, 1931 1,864,786 Wilkins June 28, 1932 2,159,162 Johnson May 23, 1939 2,360,908 Stoner Oct. 24, 1944 2,410,807 Brennen Nov. 12, 1946 2,454,098 Schmidt Nov. 16, 1948 2,466,651 Zagar Apr. 5, 1949 

